Fix for issue 229 to accept individual vlans in accepted-vlans parameter

[mmudigon]

'allowed-vlans' parameter in interfaces with 'trunk' policy accepts only 'all', 'none' and vlan-ranges like 20-30 etc. There is no way for users to specify distinct individual vlans which are not contiguous. This code update handles these cases and enables users to input distinct individual vlans as part of 'allowed-vlans' parameter.